Abstract: In this work, the reaction process of alumina adsorption of hydrogen fluoride was studied by using quantum chemical theory. Density functional theory (DFT) was used to study the adsorption behavior of hydrogen fluoride molecule on the surface of cage-like cluster composed of four alumina molecules by using Gaussian. The appropriate approximate structures were obtained by scanning the system composed of alumina cluster and hydrogen fluoride molecule. The actual transition state structure was obtained by further optimization analysis of the structure. Based on this transition state structure, the intrinsic coordinate reaction (IRC) calculation was carried out to determine the adsorption reaction process and simulate the approximate adsorption reactant and product structure. The structures of reactant and product corresponding to both ends of the IRC curve were further optimized. In addition, the energy of reactant, transition state and product in the adsorption process was calculated by Shermo. According to the calculation results, the energy line diagram of the adsorption process was drawn. The bond order was calculated to analyze the change of chemical bond during the adsorption reaction. The results showed that the adsorption of hydrogen fluoride on alumina was chemical adsorption, and the total adsorption energy was -267.5 kJ/mol. There were two continuous stages of the adsorption process. The specific adsorption process was as follows. First, hydrogen fluoride molecule was dissociated. Fluorine atom and hydrogen atom were adsorbed on tricoordinate aluminum atom and its adjacent oxygen atom, respectively. At this time, the alumina cluster underwent certain deformation. Second, the hydrogen atom moved to bicoordinate oxygen atom, surmounted a potential energy barrier, and was adsorbed on it. In the process of hydrogen atom moving, the fluorine atom was adsorbed on the tricoordinate aluminum atom all the time. After the second stage of adsorption, the original deformed cluster was restored. According to the calculated value of the reaction equilibrium constant, it was thought that the adsorption reaction can occur spontaneously at room temperature.

Key words: alumina, hydrogen fluoride molecule, adsorption, density functional theory, computer simulation, cluster

摘要： 使用密度泛函理论(DFT)对氟化氢分子在由四个氧化铝分子组成的笼状团簇结构表面的吸附行为进行了研究。对吸附过程进行了模拟，并计算了吸附结构、能量以及键级的变化。结果表明，氟化氢分子发生了化学解离吸附，其总吸附能为-267.5 kJ/mol，该吸附过程为强吸附。整个吸附过程分为两个阶段，首先氟化氢分子解离，解离后的氟原子和氢原子分别吸附在三配位铝及其相邻的氧上；然后氢原子向双配位氧转移，跨越势垒，最终吸附在双配位氧处，而氟原子始终吸附在三配位铝处。

关键词: 氧化铝, 氟化氢分子, 吸附, 密度泛函理论, 计算机模拟, 团簇